1. Field of the Invention
The present invention relates to the field of image-guided surgery, and particularly to apparatus for the simulation of such surgery, such as may be used for pre-planning, teaching or research purposes.
2. Background
Minimally invasive therapeutic procedures, including surgery and interventional radiology, reduce patient discomfort, hospital stay, and medical costs. The socioeconomic impact of compensation for lost work time is also reduced. Interventional radiology began as a tool for diagnosing and treating vascular disease (defects, notably narrowing in arteries) by catheters that move along the blood vessel and guided by fluoroscopy. The interventional radiologist uses a catheter passed into a blood vessel through a puncture in the skin to gain internal access to the site of disease. The catheter is then used as a conduit to pass therapeutic devices to treat the condition. Its principle advantages include direct surgical exposure by cutting through the flesh is not needed, and many of the procedures are performed on an outpatient basis. This reduces cost and the discomfort to the patient, as well as the time of convalescence.
Such procedures are typically carried out in a cardiac CathLab, where a physician wishes to assess the functions of the heart and coronary artery anatomy, or to perform procedures such as coronary angioplasty.
Most radiology yields recorded images: 2D X-ray film, or 3D CAT/MRI scans. xe2x80x9cLivexe2x80x9d radiology (fluoroscopy) that yields current images of a changing situation allows the radiologist to work with its guidance. Interventional radiology is the specialty in which the radiologist utilizes xe2x80x9clivexe2x80x9d radiologic images to perform therapeutic, as opposed to only diagnostic procedures. Interventional radiologists currently rely on the real-time fluoroscopic 2D images, available as analog video or digital information viewed on video monitors.
But these procedures involve delicate and coordinated hand movements, spatially unrelated to the view on a video monitor of the remotely controlled surgical instruments. Depth perception is lacking on the flat video display, and it may be hard to learn to control the tools through the spatially arbitrary linkage. A mistake in this difficult environment can be dangerous. Therefore, a high level of skill is required, and realistic training of these specialists is difficult. In addition, there is no direct engagement of the depth perception of the radiologist, who must make assumptions about the patient""s anatomy to deliver therapy and assess the results.
Medical simulators that can be used to train such medical specialists have significant potential in reducing healthcare costs through improved training, better pre-treatment planning, and more economic and rapid development of new medical devices. They shift the traditional see one, do one, teach one paradigm of medical education to one that is more experienced-based. Hands-on experience becomes possible in training, before direct patient involvement that will carry a significant risk.
Image-guided procedures, such as vascular catheterization, angioplasty, and stent placement, are specially suited for simulation because they typically place the physician at-a-distance from the operative site manipulating surgical instruments and viewing the procedures on video monitors.
In the medical field of simulation there are a number of technical challenges to overcome. The difficulties in providing hand-feeling haptic device and in creating a realistic simulation environment with a close-to-life resemblance of the operative site for controlling and manipulating the movements of simulated medical equipment has actually dampened the development of the simulators for image-guided surgery. The haptic xe2x80x9cfeelxe2x80x9d, for example, gives the surgeons another measure, beside the fluoroscopic image displayed on the video monitor, to navigate the catheter into a desired vessel. It is therefore extremely important to provide a haptic device with an interactive hand-feeling capability in an image-guided simulation system.
There are a few known simulation devices developed for this purpose. In U.S. Pat. No. 5,609,607, issued on Sep. 26, 1994, Hechtenberg et al have proposed an approach to build a device for modeling or simulating the sense of touch in a surgical instrument. It aims to provide the feeling of tissue-like contact on a layer member for surgical simulation.
Researchers at Georgia Tech have created a device incorporating virtual reality to simulate the look and feel of eye surgery, described in U.S. Pat. No. 5,766,016 (Sinclair et al), issued on Jun. 16, 1998. It has linear tactile feedback for real-time feel of tool-tissue interaction through three sets of levers and hinges to three servo-motors which collectively generate a resistive force along any direction.
In an article titled xe2x80x9cA virtual surgery simulator using advanced haptic feedbackxe2x80x9d, published in Journal of Minimally Invasive Therapy and Allied Technologies, Volume 6/2, pp 117-121, Playter et al describe a method to provide a sense of touch. Users hold real medical instruments and touch, grasp, and suture two simulated tube organs as they practice end-to-end anastomosis procedures.
Barnes et al also proposed a haptic (force feedback) interface device for the purpose of angioplasty surgery simulation. This is described in an article titled xe2x80x9cThe realization of a haptic (force feedback) interface device for the purpose of angioplasty surgery simulationxe2x80x9d, in Journal of Biomedical Sciences Instrumentation, Volume 33, pp 19-24.
There is a need, not satisfied by the prior art, to provide accurate determination of the actual motions and forces imparted upon the proximal portion of the navigating devices (e.g. catheters, guidewires, etc) and, at the same time, to create a realistic simulation of image manipulation and device control.
It is an object of the invention to overcome, or at least ameliorate, one or more of the disadvantages or deficiencies in the prior art.
The invention in one aspect provides apparatus for use in simulated image guided surgery, comprising:
positional transducer means responsive to a thin flexible member that can be manipulated by a user, the transducer means producing signals representative of displacement and rotation of said flexible member;
clamping means located proximate said transducer means, and operable to respond to a controlling signal to apply a predetermined variable clamping force to the flexible member; and
processor means receiving said displacement and rotation signals, and programmed to plot the path of the flexible member therefrom as it is manipulated by the user, and to produce said controlling signal in response to the instantaneous position along the path.
The invention in another aspect further provides a system for the simulation of image guided surgery, comprising:
a thin flexible member that can be manipulated by a user;
positional transducer means responsive to said flexible member to produce signals representative of displacement and rotation of said flexible member;
clamping means located proximate said transducer means, and operable to respond to a controlling signal to apply a predetermined variable clamping force to the flexible member;
processor means receiving said displacement and rotation signals, and programmed to plot the path of the flexible member therefrom as it is manipulated by the user and to produce said controlling signal in response to the instantaneous position along the path taken form a predetermined simulation of the path; and
display means, coupled to the processor means, to display an image of at least the instantaneous position of the flexible wire therealong.
The invention in another aspect further includes a method for the simulation of image guided surgery, the method comprising the steps of:
transducing the displacement and rotation of a thin flexible member manipulated by a user;
plotting the path of the flexible member along a simulated path representing vasculature;
user selectably displaying an image of the instantaneous position of the flexible member along the path and/or a portion of the path; and
applying a predetermined variable clamping force to the flexible member in accordance with the instantaneous position of the flexible member.
Embodiments of the invention can be used to simulate the manual positioning of a catheter and guidewire, as well as the haptic forces exerted by the user""s hand and fingers in that positioning. Other embodiments can simulate the process of balloon angioplasty, including stent deployment.
Embodiments of the invention offer a number of advantages in that a realistic simulation of image guided surgery is provided whereby all the input variables or controls that are experienced in real image guided surgery are included. Particularly a force feedback mechanism to provide a representative tactile sense to the user is achieved, and this assists in the training or pre-planning of surgery.